OLFACTORY ENSHEATHING GLIA - PROPERTIES AND FUNCTION

The failure of regenerating axons to grow within the adult mammalian c entral nervous system (CNS) does not apply to the olfactory bulb (OB), In this structure, normal and transected olfactory axons are able to enter, regenerate, and reestablish lost synaptic contacts with their t argets, throughout the lifetime of the organism. A remarkable differen ce between an axonal growth-permissive structure such as the OB acid t he remaining CNS resides in the presence of ensheathing glia in the fo rmer. These cells exhibit phenotypic and functional properties known t o be involved in the process of axonal elongation that may explain the permissibility of the OB to axonal growth, In addition, transplants o f ensheathing glia were successfully used to promote axonal regenerati on within the injured adult CNS, The axonal growth-promoting propertie s of ensheathing glia make the study of this cell type interesting to provide an insight into the mechanisms underlying the process of axona l regeneration. Therefore, in this article we review the developmental , morphologic, immunocytochemical, and functional properties presented by this unique glial cell type, and correlate them with the axonal gr owth-promoting ability of ensheathing glia, In addition, we provide so me evidence of the potentiality that ensheathing glia might have as a promoter of axonal regeneration within the injured nervous system. (C) 1998 Elsevier Science Inc.